Numerical Simulation of Rainfall Infiltration into Disposal Cover of Performance Test Facility

Mijin Kwon, Seho Choi, Chunhyung Cho

Korea Radioactive Waste Agency, 174, Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea

Received 2024-01-21 ; Revised 2024-02-13 ; Approved 2024-03-22

Abstract

Disposal cover as an engineered barrier of a near-surface disposal facility for low and very low-level radioactive waste is composed of a multi-layer to isolate radioactive waste from environmental influences for the long term. To acquire a realistic forecast for the post-closure period of the disposal facility, it is essential to carry out long-term experimental research in a similar condition to the actual disposal environment. Under this circumstance, a performance test facility of the disposal cover was constructed in Gyeongju LILW disposal center in 2022. The constructed performance test facility has differences from the material properties presented in the design. These differences are factors that affect the prevent rainfall infiltration, which is one of the important roles of the disposal cover. Therefore, in this study, a numerical simulation of rainfall infiltration into the performance test facility was performed for the designed case and the actual constructed case. To simulate the behavior of water infiltration, the FEFLOW software based on the finite element method was used. Through the analysis of numerical simulation results, it is confirmed that the hydraulic conductivity of the material constituting the multi-layer of the disposal cover greatly influenced the amount of water infiltration.

Key Words : low and intermediate-level radioactive waste, disposal cover, performance test Facility, rainfall infiltration, near-surface disposal facility